Various different wiring devices for delivering power or communications connections to floor-mounted plug-in receptacles have been proposed in many different patents. U.S. Pat. Nos. 1,869,841, 3,081,896, 3,166,633, 3,318,476, 3,972,579 and 3,751,576 all relate to various products of this kind. Heat and fire resistant materials blocking the passage of smoke, flame or heat through wall or floor openings in and around electrical wiring receptacles and their associated raceways have also been mentioned in various patents such as U.S. Pat. Nos. 3,255,556, 3,455,850, 3,336,153, 2,279,791 and German Offenlegungsschrift No. 2,162,251 dated June 20, 1973 Offenlegungstag. Incorporation of ceramic fiber products as fire resistant materials in floor aperture mounted poke-thru wiring devices was suggested in U.S. Pat. No. 3,803,341. The use of intumescent expanding or foaming material such as sodium silicate or other water-containing alkali metal silicates in specified shapes and orientations, to swell in response to heat or flame, blocking the thru floor aperature and retarding the passage of smoke, heat or flame therethrough in poke-thru wiring devices is suggested in U.S. Pat. Nos. 3,395,102 and 4,099,020.
These prior conventional poke-thru wiring devices have customarily required the cooperation of two installing electricians, one working below the floor and one working above the floor to raise a junction box and tubular hollow conduit column inserted from below upwardly through the floor opening to be assembled with downwardly extending portions of a "tombstone" receptacle mounted above the floor opening and standing above the floor level. After assembly, a cover or housing has customarily been assembled to complete the tombstone receptacle installation.
Accordingly, there has been a long standing need for a unitary insertable poke-thru wiring device capable of installation from above the floor which could be inserted and lowered into place and which would then anchor itself in position without the attention of any electrician or installer below the floor.